The tech IPO was not originally created as a company at all.

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Mark Zuckerberg, founder and chief executive officer of Facebook Inc., center, leaves the Sheraton hotel in New York, U.S., on Monday, May 7, 2012. Zuckerberg is meeting would-be investors today as the largest social-networking service begins marketing its initial public offering, said a person with knowledge of the matter. Photographer: Scott Eells/Bloomberg via Getty Images

Facebook will offer stock in an IPO the company never wanted, which will earn it billions of dollars it does not appear to need.

In fact, much like Google, Facebook was not even originally created to be a company.

"It was built to accomplish a social mission — to make the world more open and connected," founder and CEO Mark Zuckerberg warned in the company's filing.

Estimates put the IPO's value at $12 billion - though that number changes often. That's $13 billion for a company that already has $3.9 billion cash on hand and is on track for net revenues of around a billion dollars per year.

While it has far less cash on hand than Apple or Google, that's still an enormous pile of dollars it's not using and has no plans to use.

"We do not currently have any specific uses of the net proceeds planned," says Facebook in the dry legalese of its financial filings.

In fact, the company plans to invest the money in the least interesting way, by buying savings bonds: "Pending other uses, we intend to invest the proceeds to us in investment-grade, interest-bearing securities such as money market funds, certificates of deposit, or direct or guaranteed obligations of the U.S. government, or hold as cash."

Though of course Facebook didn't have any obvious plans to buy Instagram for a $1 billion.

So a company that didn’t want to be a company will raise money it doesn't need. Why IPO at all?
Turns out, it didn't necessarily want to do that either. Many point to the "500 rule" (see page 148) as the cause behind Facebook's filing.

"The rule mandates that once a private company has more than 500 investors, it must begin releasing quarterly financial information to the Securities and Exchange Commission, just as public companies do" explains CNBC reporter Kate Kelley.

In June of last year, Facebook COO Sheryl Sandberg called the IPO "inevitable." The 500 shareholder rule became even more problematic when Goldman Sachs received a chunk of Facebook insider shares and divided them up for resale.

(One should note the 500 rule does not require a company to go public - rather it creates responsibilities and difficulties required of public companies. Put another way, Facebook would get all the pain and none of the benefits - it might as well offer stock.)

Ironically, that requirement vanished with the passing of the recent JOBS Act. "It's interesting to wonder", says Yammer CEO David Sacks. "If they would still be IPOing if that rule weren't around [at the time]." See more of Sack's interview here.

There are of course many reasons to offer shares beyond just making money: Giving your investors a way to exit - a payout. Giving your employees a reason to stick around and not jump ship to a soon-to-IPO company.

The Facebook IPO may be the most anticipated since Google's first public offering. It may even rival the excitement over Netscape. However, it's also one of the most peculiar.